• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.434-444
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• 2021

The decrease in fatness of the Pacific oyster Crassostrea gigas, which consequently results in decrease in the profit of aquaculture industry, has become a source of serious concern in southeast coast of Korea. The ratio of flesh (edible portion) to total oyster weight, commonly called edible portion yield ("suyul" in Korean), have been used as a fatness index for the healthy and valuable state of oyster from the early stage of oyster farming in Korea. More than 360 data sets were collected from early culturing periods (in the 1970s) to the present from approximately 15 published literatures to evaluate the long-term fatness trend of oyster, reared particularly in submerged longline culturing system in Gyeongsangnam-do province. Slight decrease in oyster fatness during the 1970s to 1990s was detected in Tongyeong and Geoje Bays; however, from the 1990s to the present, clear decreasing trends were observed with a decrease of 0.04-0.08% year^-1, especially during harvest season. Oyster mass production per unit area almost doubled within a short period in the early 2000s; however, changes in coastal environment factors inhibited the fattening of shellfish from the mid 1990s. These results indicate that the severe competition in feeding and low biological production in water column might be some convincing reasons for the decrease in fatness of oyster from the 1990s, in Tongyeong and Geoje Bays, Korea.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.17-21
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• 2001

The object of this study is to find out the characteristics of waste oyster shells and determine the proper dosage of powdered waster oyster shells as the conditioning agent for water treatment sludge dewatering process. The large amount of waste oyster shells which discharges from the oyster farming, occurs serious environmental hazards. However, oysters shell contain large amount(about 38% by weight) of alkaline minerals, such as calcium and magnesium and so on, this natural material is thought to have the petential ability as a good conditioning agent. The results of this study are as follows. The optimum condition for improvement of the water treatment sludge dewaterability is when 6 g of waste oyster shell powder added to 200$m\ell$ of water treatment sludge. At optimum condition, the solid contents can reach to 31.78% and the specific resistance of conditioned sludge is 0.16$\times$10$^{8}$ sec$^2$/g. However, exceeding the of powdered waste oyster shell is needed to get the effective result. Consequently, the waste oyster shell can be a recyclable material to improve the dewaterability of water treatment sludges.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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• pp.382-389
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• 2021

By applying super-high pressure (150-250 MPa) to a sealed pressure vessel, it is possible to make oyster shucking machine that automatically opens two-sheet shellfish or oysters. Possibility of developing a shucking machine was confirmed by identifying the working pressure for meat of oysters produced in the southern coast and conducting sensory evaluation of meat oysters. As a result of confirming the shucked oysters under super-high pressure of 150 MPa in the pressure vessel, the number of type A with separated shells and well-separated meat was 22 and type B with both shells and internal meat and shells not separated. For the oysters that were treated at 175 MPa, there were 58 type As with shell separated and meat well separated and 42 type Bs without oyster shells and insides. When looking at the oysters shucked at 200 MPa in the pressure vessel, the number of type A was 86 and type B was 14 accounting for 86% of oysters with good marketability. As a result of shucking oysters by applying 250 MPa, 96% type A oysters and 4% type B oysters were obtained from the total specimen. The total specimen oyster weight used in the conducted experiment was 6 kg, the average oyster shell weight was 3.99 kg and the average oyster meat weight was 1.25 kg. Therefore, the fatness of oyster meat, which measures the added value of oysters, is 20.8%. Sensory evaluation was conducted on thinned oysters by hand and type A oysters shelled by machine with an operating pressure of 200 MPa. The hand-worked oyster sample scored 4.7 points only in salty taste, and scored 5.0 or higher in color, shape, smell, fishy taste, texture and preference.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.1075-1082
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• 2014

Monthly Screening of Pacific oyster, Crassostrea gigas, was surveyed by PCR for Ostreid herpesvirus(OsHV-1) infections from 2012 to 2013 in Korea. It was showed positive results in one hatchery in April and May 2012 and in oyster farming areas from August to November in 2013. The obtained sequences showed 99.3~99.5% homology with OsHV-1 ${\mu}var$(Accession Number: HQ842610) and 96.2~96.3% homology with OsHV isolated from Korea(Accession Number: AY509253).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.45-56
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• 1980

Farming density of oyster cultured in Hansan-Geoje Bay was studied to obtain the optimal farming density based on the biosedimentation analysis and the annual yield data from 1970 to 1979. Farming density of oyster extrapolated by means of pollution grade of sediment is significantly correlated to COD and phaeophytin content of the bottom mud of the bay. Pollution grade is linearly related to the number of oyster clusters suspended in the unit area. Optimal farming density was $0.12\;string/m^2$ in case of raft culture, and it was $0.12\;string/m^2$ in case of long-line culture. Farming density was well expressed by the number of strings per raft and the area covered by a raft. As strings per raft increased from 350 to 558, total yield from a raft increased and when occupied sea area per raft ranged from $1.000\;m^2\;to\;6,000\;m^2$, the yield per raft linearly increased as the area increased. This analysis suggests that the optimal density be 0.11 string per unit area $(m^2)$. As increasing the number of strings per $m^2$ the yield per string decreases, and this is well dipicted by a linear function. At this time the yield per unit area increases when the number of string increases up to the density of $0.13\;strings/m^2$. From the point of these three comprehensive analyses the optimal density was $0.11\~0.13\;string/m^2$ in case of raft culture and $0.25\;strings/m^2$ in case of long-line culture in Hansan-Geoje Bay. The maximum expected yield of oyster in Hansan-Geoje Bay is approximately 5,600 tons when maintained the string density at $0.11\~0.13\;string/m^2$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.7
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• pp.106-111
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• 2020

In the era of the fourth industrial revolution, the application of big data analysis technology is crucial in various industries. In this regard, considerable research is necessary to improve aquafarming productivity, particularly in fish culture, which is one of the primary industries in the world. In this study, a sample experiment using a flop was conducted to improve oyster productivity in fish farms, and a flush was installed in an environment similar to aquaculture farms. Thereafter, the temperature data of the water environment where the formation of burrows considerably improved were collected; the growth rate of burrow seeds was also measured. The gathered experimental data were examined by time series data analysis. Finally, a system that visualizes the analysis results based on big data is proposed. In accord with the results of this study, it is expected that more advanced research on the productivity improvement of oyster aquafarming will be performed.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.2
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• pp.71-76
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• 2001

Recently, sludge disposal becomes one of the most serious environmental problems. Because the landfilling and ocean dumping of sludge materials will be prohibited in the near future, the proper treatment?disposal methods should be investigated. Also, oyster shells, piled at the coast, cause adverse effects in coastal fishery, public water surface, natural landscape, public health and so on. Thus, the purpose of this study is to evaluate the dissolution characteristic of metal compounds during soil application experiment using sewage treatment sludge mixed with oyster shells. The dissolution experiment conducted 100days under artificial rainfall and farming soil, mixed with sewage treatment sludge and oyster shells, was put into the pots(approx. 0.5L). The results from dissolution experiment as follows. 1. K, Na was $5{\sim}20mg/{\ell}$, and Ca was less than $90mg/{\ell}$. 2. Heavy metals such as Cd, Cu, As, Pb, Cr, Hg are dissoluted far less than the soil pollution guideline. The application of sewage sludge mixed with oyster shells increases pH(soil acidity)and buffer capacity(CEC) of farming soil, and heavy metals are thought to be attached to soil as insoluble forms.

• Journal of Mushroom
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• v.13 no.2
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• pp.135-138
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• 2015

'Daejang 3ho' is a new cultivar of oyster mushroom for high productivity than that of Chunchu 2ho. This cultivar was bred by Di-mon mating between monokaryotic strains isolated from 'Daejang 1ho' and dikaryotic strain 'Jangan 5ho'. The color of pileus and the shape of pileus of new cultivar were dark gray and deeply funnel shape, respectively. The length and thickness of stipe were longer and thicker than those of Chunchu 2ho. It took 4~5 days to formation of primordia, that was a similar to Chunchu 2ho. The optical temperature of fruit body was $14-17^{\circ}C$. Yield of 'Daejang 3ho' was 13.9% higher than that of Chunchu 2ho. Analysis of RAPD by URP-primer of #03, #08, #10 and #11 showed that different band pattern those of other strains. There were no significant differences between the texture properties of 'Daejang 3ho' and Chunchu 2ho.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.475-490
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• 2012

Since 1997, Korean Ministry of Knowledge Economy and Ministry of Environment have established data on some 400 basic raw and subsidiary materials and process like energy, petro-chemical, steel, cement, glass, paper, construction materials, transportation, recycling and disposal etc by initiating establishment of LCI database. Regarding agriculture, Rural Development Administration has conducted establishment of LCI database for major farm products like rice, barley, beans, cabbage and radish etc from 2009, and released that they would establish LCI database for 50 items until 2020 later on. The domestic LCI database for seeds, seedling, agrochemical, inorganic, fertilizer and organic fertilizer etc is only at initial stage of establishment, so overseas LCI databases are brought and being used. However, since the domestic and overseas natural environments differ, they fall behind in reliability. Therefore, this study has the purpose to select organic farming materials, survey the production process for various types of organic farming materials and establish LCI database for the effects of greenhouse gas emitted by each crop during the process. As for selecting methods, in this study organic farming materials were selected in the method of direct observation of material and bottom-up method a survey method with focus on the organic farming materials admitted into rice production. For the basic unit of carbon emission amount by the production of 1kg of organic farming material, the software PASS 4.1.1 developed by Korea Accreditation Board under Ministry of Knowledge Economy was used. The study had the goal to ultimately provide basic unit to calculate carbon emission amount in executing many institutions like goal management system and carbon performance display system etc in agricultural sector to be conducted later on. As a result, emission basic units per 1kg of production were calculated to be 0.04968kg-$CO_2$ for oystershells, 0.004692kg-$CO_2$ for expanded rice hull, and 1.029kg-$CO_2$ for bordeaux mixture liquid.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.1-9
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• 2016

Oysters are rich in nutrients with good flavor, and disease prevention is required in both the East and the West for high-quality seafood. The best way to store and transport mass-produced oysters is using dry techniques. Using both hot and frozen drying technologies to obtain a perfectly dried oyster often destroys much of the flavor and nutrients found with the oyster meat. This study uses a low temperature vacuum drying technology to investigate the final weight ratio of wild and farmed dried oysters. Additionally, the heat transfer characteristics of steamed oysters are discussed in this paper.